Synthesis and characterization of grafting polystyrene from guar gum using atom transfer radical addition

To broaden the application fields for guar gum, this natural polymer is often grafted to/from the surface to modify its properties. Polystyrene-guar gum (PS-guar gum) is successfully synthesized using atom transfer radical addition based n-BuBr(C₄H₉Br), Cu(I)Cl and N,N,N',N″,N‴-penthamethyldiethylenetriamine (C₉H₂₃N₃,PMDETA) as initiator, electronating agent and ligand respectively in an inert atmosphere. The graft copolymer is characterized by FT-IR, ¹H NMR, XRD and scanning electron microscope (SEM). The results show that styrene is successfully introduced onto guar gum and particles of PS-guar gum adopt a disordered morphology with diameters of 100nm, and PS-guar gum are largely amorphous with poor crystallinity. Besides, add on shows an increasing trend on increasing the concentration of PS. Swelling behavior, hydrophobicity and thermal stability of PS-guar gum indicate that PS-guar gum has great thickening capacity and thermal stability. Nevertheless, modification of guar gum via ATRA truly is convenient to industrial production since facilitating the manufacturing process.